The present study was conducted to evaluate the in vitro efficacy of native Trichoderma spp. against Pythium spp. and Rhizoctonia solani (Kuhn.) causing damping-off disease in Tomato. One hundred eighty soil samples were collected from 11 districts of Meghalaya and ninety seven Trichoderma isolates were obtained. Rapid screening against damping off pathogens (Pythium spp. and R. solani) of tomato revealed that 20 isolates showed maximum antagonism and subsequently 20 best isolates were selected for further analysis. Isolate TR 55 isolated from tomato rhizosphere was found to be the most effective isolate against both Pythium spp. and R. solani Kuhn, showing an inhibition percentage of 89.26% and 87.41% respectively, followed by other isolates like TR 66, TR 122 and TR 136. Screening for the PGPR and biocontrol potential of the twenty potential isolates revealed that all isolates were found positive for IAA production, ACC deaminase production and phosphorous solubilization, whereas 17 positive for chitinase production, 16 isolates were found positive for siderophore and ammonia production and 13 isolates were positive for HCN production.
Trang 1Original Research Article https://doi.org/10.20546/ijcmas.2019.802.064
In vitro Efficacy of Native Trichoderma Isolates against Pythium spp and Rhizoctonia solani (Kuhn.) causing Damping-off Disease in Tomato
(Solanum lycopersicum Miller)
Markidahun Biam*, Dipali Majumder and Heipormi Papang
Department of Plant Pathology, College of Post Graduate Studies, Central Agricultural
University, Umiam-793103, Meghalaya, India
*Corresponding author
A B S T R A C T
Introduction
Tomato (Solanum lycopersicum Miller) is one
of the most important temperate vegetable
crops throughout the world and is also widely
cultivated in Meghalaya, India Tomato
production has a major role in global
horticulture, ranking second in importance
next to potato in many countries (Sharma et
al., 2014) The main advantage of tomato
farming is that it can be grown either in the
field or under greenhouse conditions Tomatoes are a good source of potassium, vitamin C, vitamin A and excellent antioxidant lycopene They help in fighting cancer, reducing heart disease and are also good for eye health and digestion (Nahar and Ullah, 2012)
China is leading producer among Asian countries, followed by India In India, tomato
is cultivated as one of the leading vegetable
International Journal of Current Microbiology and Applied Sciences
ISSN: 2319-7706 Volume 8 Number 02 (2019)
Journal homepage: http://www.ijcmas.com
The present study was conducted to evaluate the in vitro efficacy of native Trichoderma spp against Pythium spp and Rhizoctonia solani (Kuhn.) causing damping-off disease in
Tomato One hundred eighty soil samples were collected from 11 districts of Meghalaya
and ninety seven Trichoderma isolates were obtained Rapid screening against damping off pathogens (Pythium spp and R solani) of tomato revealed that 20 isolates showed
maximum antagonism and subsequently 20 best isolates were selected for further analysis Isolate TR 55 isolated from tomato rhizosphere was found to be the most effective isolate
against both Pythium spp and R solani Kuhn, showing an inhibition percentage of 89.26%
and 87.41% respectively, followed by other isolates like TR 66, TR 122 and TR 136 Screening for the PGPR and biocontrol potential of the twenty potential isolates revealed that all isolates were found positive for IAA production, ACC deaminase production and phosphorous solubilization, whereas 17 positive for chitinase production, 16 isolates were found positive for siderophore and ammonia production and 13 isolates were positive for HCN production
K e y w o r d s
Meghalaya,
Damping off,
Trichoderma spp.,
Pythium spp.,
Rhizoctonia solani,
Tomato, per cent
inhibition, PGPR
and biocontrol
potential
Accepted:
04 January 2019
Available Online:
10 February 2019
Article Info
Trang 2crops, covering an area of 8.65 lakh hectares
with a total production of 168.26 lakh tonnes
having productivity of 19.60 tonnes ha-1
(Anon, 2014) Bihar, Karnataka, Odisha,
Maharashtra, Himachal Pradesh, West
Bengal, Tamil Nadu, Uttar Pradesh and
Gujarat are major tomato growing states
(Ghinaiya and Pandya, 2017) and among
them Karnataka is the largest producer state in
India These States account for 91% of the
total production of the country Meghalaya
accounts for 36.60 million tonnes of tomato
production, which is 0.16 % of country’s total
tomato production (Anon, 2018)
Although tomato is commercially grown
across the globe, there is no place where the
plant is free from diseases One of the major
causes of seedling loss is damping-off, a
disease that is mainly caused by Pythium spp
and Rhizoctonia solani Kuhn, which are
responsible for seed decay as well as
pre-emergence and post-pre-emergence damping-off
of tomato seedlings Most of these fungi can
also cause cuttings to rot (Thakur and
Tripathi, 2015)
Management of damping off by fungicides is
not the most desirable means of disease
management, for several important reasons
Fungicides are heavily regulated and
additionally, they are expensive, cause
environmental pollution, and may induce
pathogen resistance (Lamichhane et al.,
2017) Since cultural practices alone are not
always sufficient to effectively manage the
disease, alternative strategies are needed
Therefore, management of plant pathogens
using microbial bio inoculants has been
considered as a potential management
strategy for integrated disease management
Many researchers have demonstrated the
potential of Trichoderma spp in management
of damping-off diseases of crop plants caused
by Pythium spp (Lamichanne et al., 2017;
Majeed et al., 2018; Al-shemamary et al.,
2018) and Rhizoctonia solani (Asad et al., 2014; Abbas et al., 2017; Mangariello et al.,
2018) Trichoderma spp are widely distributed all over the world and found in all natural habitats especially in those containing
forest humus layer (Wardle et al., 1993) as well as in agricultural orchard soils (Roiger et
al., 1991) and soil consisting of organic
matter (Papavizas, 1985) It is known to be one of the best candidates of BCA against wide range of plant pathogens
Therefore, in the present investigation major
emphasis was to study the bio-efficacy of native Trichoderma isolates against damping off caused by Pythium spp and Rhizoctonia
solani Kuhn
Materials and Methods Isolation, identification and maintenance of pathogen
Pythium spp and R solani Kuhn were
isolated from naturally infected tomato, showing damping off symptoms (soft rot and
wire stem symptom for Pythium spp and R
solani respectively) and pathogenicity test
was carried out in SCP, CPGS, CAU, Umiam, Meghalaya Diseased samples collected from farmers’ fields were brought to laboratory and isolations were done With repeated
isolations, Pythium spp and R solani Kuhn
were consistently found with the infected
seedlings of tomato Pythium spp cultures
isolated from the infected tomato seedlings were identified based on the types of fungal mycelium and filamentous sporangia with terminal, smooth and spherical oospores as compared with the old cultures available in
the Laboratory Also R solani Kuhn was
identified based on the hyphae that tend to branch at right angles and a septum near each and a slight constriction at the branch are diagnostic The fungus was purified by hyphal tip cut method The purified culture was
Trang 3maintained on PDA slants at 4˚C in
refrigerator
Collection and isolation of Trichoderma
from different locations of Meghalaya
Soil samples from root rhizosphere, coal
mines, jhum fallows, manure compost and
submerged areas were collected from 11
districts of Meghalaya Isolation of
Trichoderma was done by dilution plate
method using PDA (Dhingra and Sinclair,
1995) One gram of soil was suspended in 250
ml Erlenmeyer flasks with 100 ml sterilized
distilled water Samples were shaked for
20-30 minutes on a rotary shaker at 250 rpm and
dilutions of 10-1, 10-2, 10- 3, 10-4 and 10-5 were
made for each soil samples An aliquot of 0.1
ml of substrate suspension was dispensed on
PDA The Petriplates (90mm in dia) were
incubated at 28 ± 1ºC for 24 hours
Morphologically distinct colony was isolated,
purified and grown in pure culture on PDA
The obtained fungal isolates were grown on
PDA slants and kept at 4°C until being used
Isolated Trichoderma was grown on Malt
Extract Agar (MEA) medium and identified
based on characters viz conidiophores,
phialides and conidia (Rifai, 1969; Bisset,
1992) Microscopic examination was carried
out by mounting the culture in lactophenol
cotton blue
Rapid screening of Trichoderma isolates
Isolates tentatively identified as Trichoderma
were exposed to rapid screening of
Trichoderma isolates against Pythium spp
and R solani Kuhn by dual culture technique
on PDA medium on the basis of their relative
growth rate measured as a function of
incubation period Mycelial discs of 5mm
diameter was picked up from the margin of
young 3-4 days old culture of Trichoderma
and the respective pathogens were inoculated
at the peripheral region of the Petriplates
(90mm in dia) at equal distance from the centre and incubated for 5-6 days at 28±1°C The relative growth rate of test antagonist and the pathogen were observed and recorded
The most efficient Trichoderma isolate was
sorted out as potent isolate against the respective pathogen These isolates were multiplied and maintained as mentioned earlier for long term preservation and preserved at 4°C in PDA slants for subsequent use
The Trichoderma isolates were rated on the
basis of their ability to suppress the mycelia growth of pathogen following the methods of
modified Bell’s scale (Bell et al., 1982)
S1: The antagonist completely overgrew the pathogen (100% over growth)
S2: The antagonist overgrew at least 2/3rd growth of the pathogen (75% overgrowth) S3: The antagonized colonized half of the growth of pathogen (50% overgrowth)
S4: The pathogen and antagonist (locked at the point of contact)
S5: The pathogen overgrew the antagonist The experiment was conducted with three replicates per treatments
Efficacy of Trichoderma isolates against
Pythium spp and R solani Kuhn
The potential Trichoderma isolates were
further evaluated for their antagonistic
potential in vitro against Pythium spp and R
solani Kuhn through dual culture technique
(Ramanathan et al., 2013)
Dual culture technique
For mycelial growth inhibition of test plant
pathogens by the Trichoderma spp., both pathogens (Pythium spp, R solani Kuhn.) and
antagonists were inoculated at peripheral region opposite to each other in sterilized Petriplates (90 mm dia) containing 20 ml
Trang 4sterilized PDA medium and incubated at
28±1°C Plates inoculated with the pathogens
only served as the control Observation for the
dual inoculation of the Trichoderma spp and
the pathogen was taken till the growth of the
pathogen fully covered the plate The
experiment was replicated three times The
suppression effect of all Trichoderma spp
isolates were evaluated in terms of Percentage
Inhibition in Radial Growth (PIRG) of
Pythium spp and R solani based on the
following formula (Gaigole et al., 2011)
PIRG = R1- R2 x 100%
R1
R1 = Radial growth of Pythium spp and R
solani in the absence of the antagonist in the
respective plate (control)
R2 = Radial growth of Pythium spp and R
solani in the presence of the Trichoderma
isolates (treatment)
Screening of isolated Trichoderma for In
biocontrol potential
The strains of Trichoderma isolates were
determined for chitinolytic activity on chitin
detection medium (Thakar and Saraf, 2015)
Preparation of colloidal chitin
5.0 g of chitin was added to 60 ml of conc
HCl (acid hydrolysis) by constant stirring
using a magnetic stirrer at 4oC and kept in
refrigerator overnight The resulting slurry
was then added to 200 ml of ice-cold 95%
ethanol and kept at 26 °C overnight (ethanol
neutralization) Then it was centrifuged at
3,000 rpm for 20 min at 4°C The pellet was
repeatedly washed with sterile distilled water
by centrifugation at 3,000 rpm for 5 min at 4
°C until the smell of alcohol vanished The final colloidal chitin was stored at 4 °C until further use
Chitinase detection medium
The final chitinase detection medium per litre comprised of 4.5 g colloidal chitin, 0.3 g magnesium sulphate, 3.0 g ammonium sulphate, 2.0 g potassium dihydrogen phosphate, 1.0 g citric acid monohydrate, 15 g agar, 0.15 g bromocresol purple and 200ul of tween-80 The pH of the media was maintained at 4.7 and autoclaved at 121 °C for 15 min The fresh culture plugs of
Trichoderma isolates to be tested for chitinase
activity were inoculated into the sterile plates containing chitinase detection medium and incubated at 28 ± 2 °C for 2–3 days and observed for the coloured zone formation Formation of purple coloured zone was observed and recorded
Siderophores production test
The ability of Trichoderma spp to produce
iron-binding compounds of siderophore-type was detected in solid medium by universal
Chrome Azurol S (C.A.S) assay (Srivastava et
al., 2013)
Preparation of the C.A.S (Chrome Azurol S) Blue Agar
One litre of C.A.S blue agar was prepared using 60.5 mg C.A.S dissolved in 50 ml distilled deionized water and mixed with 10
ml iron (III) solution (1 mM FeCl3.6H2O, 10
mM HCI) Under stirring, this solution was slowly added to 72.9 mg Hexadecyl tri
dissolved in 40 ml water The resultant dark blue liquid was autoclaved for 20 min Also autoclaved a mixture of 750 ml water, 15 g agar, 30.24 g Pipes and 12 g of a solution of 50% (w/w) NaOH to raise the pH to the pKa
Trang 5of Pipes (6.8) The dye solution was finally
poured along the glass wall and agitated with
enough care to avoid foaming Petri dishes
(9cm in diameter) were prepared with 30 ml
of PDA medium for culturing Trichoderma
spp After solidification, the medium was cut
into halves, one of which was replaced by
C.A.S blue agar (15 ml) The halves
containing culture medium were inoculated
with 5 mm discs of seven days old culture of
Trichoderma strains The inoculum was
placed as far as possible, from the borderline
between the two media The plates were
incubated at 28 ± 2°C for 7 days in the dark
Colour-changed from blue to purple or dark
purplish- red (magenta) in the C.A.S.-blue
agar, starting from the borderline between the
two media was considered positive for
siderophore production The experiment was
carried out in triplicates The control plates of
C.A.S.-agar uninoculated were incubated
under the same conditions as described above
The experiment was conducted with three
replicates per treatments
Production of HCN was detected by
inoculated different isolates of Trichoderma
spp separately onto the PDA medium
amended with 4.4 g/ml glycine and lid of
plate was covered with the soaked Whatsman
no.1 filter paper in 0.5% picric acid and in 2%
sodium carbonate, then incubated for 5-7 days
at 28±1°C Change in colour of filter paper
from deep yellow to orange and finally to
orange brown to dark brown indicated the
positive reaction The experiment was
conducted with three replicates per treatments
(Dixit et al., 2015)
Indole-3-acetic acid (IAA) estimation test
Quantitative estimation of IAA was done
through addition of tryptophan in the potato
dextrose broth (PDB) for Trichoderma spp
and incubated at 25±1°C for seven days and filtered with Whatman No 2 filter paper, then
1 ml filtrate was mixed with 2 ml Salkowski reagent (2% 0.5M FeCl3 in 35% perchloric
acid) in a test tube (Gravel et al., 2007) The
mixture was incubated at room temperature for 20 minutes Pink colour producing samples was considered as positive reaction and absorbance was measured at 540 nm by spectrophotometer A standard curve was prepared using IAA and the presence of IAA
in the culture filtrate was quantified The IAA produced was compared to the standard graph
and expressed as μg/ml (Dixit et al., 2015)
Solubilization of P was tested quantitatively using 20 ml Pikovskaya’s broth medium (PKV) amended with 5 g/l tricalcium phosphate (17% P) then inoculated with a mycelial disc of seven days old culture of
Trichoderma spp and incubated at 28±1°C on
a shaker for 3-4 days Uninoculaed PKV broth served as control in each case Each experiment was done in triplicate set Mycelial growth was filtered through Whatman No 42 filter paper and 50 μl of resultrant filtrate was added with 500 μl of ammonium molybdate solution and shaked well An addition of 2ml distilled water, 13μl chlorostannous acid and 2.5 ml distilled water was made Blue colour intensity was recorded
by spectrophotometer at 600nm The available phosphorus in the culture filtrate was calculated from a standard curve prepared using various concentration of standard K2HPO4 solution and the results
were expressed in μg/ml (Rudresh et al.,
2005)
ACC deaminase production test
The ACC deaminase production of the
Trichoderma isolates was screened using the
methods described by Jasim et al., (2014) For
Trang 6this, the isolates were inoculated on to Difco
(DF) salts minimal medium (potassium
dihydrogen phosphate 4 g/L, disodium
hydrogen phosphate 6 g/L, magnesium sulfate
heptahydrate 0.2 g/L, ferrous sulfate
heptahydrate 0.1 g/L, boric acid 10 µg/L,
manganese(II) sulfate 10 µg/L, zinc sulphate
70 µg/L, copper (II) sulfate 50 µg/L,
molybdenum (VI) oxide 10 µg/L, glucose 2
g/L, gluconic acid 2 g/L, citric acid 2 g/L,
agar 12 g/L) amended with 0.2 % ammonium
sulphate (w/v) The fungal growth in this
media after 4-7 days of incubation was
considered as positive result The experiment
was conducted with three replicates per
treatments
Trichoderma isolates was tested for the
production of ammonia in peptone water
Freshly grown cultures were inoculated in 10
ml peptone water separately and incubated for
48-72 h at 36 ± 2°C Nessler’s reagent (0.5
ml) was added in each tube Development of
yellow to brown colour indicated for positive
test (Thakkar and Saraf, 2015) The
experiment was conducted with three
replicates per treatments
Results and Discussion
Soil samples collected from different
locations of Meghalaya were tested The
isolates showing the lime green to greenish
colour sporulation with highly fluffy growth
and sparse to compact colony after 7-10 days
of incubation were selected The selected
isolates were grown on Malt Extract Agar
(MEA) to observe conidiophores, phialides
and conidia Based on taxonomic keys
provided by Rifai (1969) Bisset (1992), it is
evident that altogether ninety seven (97)
Trichoderma isolates were isolated from 180
soil samples collected
Rapid screening of Trichoderma isolates was done against Pythium spp and R solani
Kuhn by dual culture in potato dextrose agar and the results showed that 77 isolates attained S4 stage (the pathogen and antagonist locked at the point of contact), 8 isolates showed S3 stage (the antagonized colonized half of the growth of pathogen i.e 50% overgrowth) and remaining 12 isolates showed S2 stage (the antagonist overgrew at least 2/3rd growth of the pathogen i.e 75% growth) from 4-7 days after inoculation on the basis of modified Bell’s scale (Plate 1)
The study of antagonistic potential of 20 screened isolates of Trichoderma spp against
damping-off pathogens which showed S2 and S3 stage on the basis of modified Bell’s scale revealed that all 20 isolates showed an inhibition percentage of more than 65%
Among which 4 Trichoderma isolates viz TR
55, TR 66, TR 122 and TR 136 were most
effective in inhibiting Pythium spp with
percent inhibition of 89.26%, 88.15%, 88.89% and 87.78% respectively, whereas
only 2 isolates viz TR 55 and TR 122 were found effective against R solani with percent
inhibition of 87.41% and 86.48% respectively (Table 1)
The result (Table 2, Plate 2) showed that out
of 20 screened isolates, only 16 isolates were positive for siderophore production as indicated by colour-changed from blue to purple or dark purplish- red (magenta) in the C.A.S.-blue agar Also 16 isolates were positive for ammonia production indicated by development of yellow to brown colour in Nessler’s reagent whereas 17 isolates were positive for chitinase and 13 isolates were positive for HCN production as evidenced by the change in the colour of filter paper However all 20 screened isolates grew on Difco (DF) salts minimal medium showing their ability to produce ACC deaminase
Trang 7Table.1 In vitro efficacy of Trichoderma isolates against Pythium spp and R solani
Sl
No
Trichoderma
isolates
(1.41)
1.90±0.06ij (1.37)
77.78±0.64e (61.88)
78.89±0.64de (62.65)
(1.56)
2.07±0.09gh (1.43)
72.96±0.74i (58.67)
77.04±0.98fg (61.37)
(1.67)
2.33±0.03cde (1.52)
68.89±0.64j (56.10)
74.07±0.37jk (59.39)
(1.49)
2.07±0.03gh (1.43)
75.19±0.74f (60.12)
77.04±0.37fg (61.37)
(0.98)
1.13±0.03o (1.06)
89.26±0.37a (70.87)
87.41±0.37a (69.22)
(1.40)
1.97±0.07hi (1.40)
78.15±0.74e (62.13)
78.15±0.74ef (62.13)
(1.03)
1.43±0.03l (1.19)
88.15±0.37a (69.86)
84.07±0.37b (66.47)
(1.41)
1.73±0.03k (1.31)
77.78±0.00e (61.87)
80.74±0.37c (63.97)
(1.35)
2.40±0.06c (1.54)
79.63±0.98de (63.18)
73.33±0.64l (58.91)
(1.39)
2.23±0.07def (1.49)
78.52±0.98e (62.40)
75.19±0.74hij (60.12)
(1.54)
2.18±0.04efg (1.47)
73.70±0.37h (59.14)
75.74±0.49ghi (60.49)
(1.25)
1.53±0.03l (1.23)
82.59±0.37bc (65.34)
82.96±0.37b (65.62)
(1.30)
2.30±0.00m (1.51)
81.11±1.28cd (64.26)
74.44±0.00ijk (59.63)
1.53)
2.12±0.10fg (1.45)
74.07±0.37fg (59.39)
76.48±1.13gh (61.00)
(1.28)
2.63±0.03b (1.62)
81.85±0.98bc (64.79)
70.74±0.37m (57.25)
(1.35)
2.35±0.05cd (1.53)
79.63±0.74de (63.17)
73.89±0.56jk (59.27)
(1.00)
1.22±0.02no (1.10)
88.89±0.00a (70.53)
86.48±0.19a (68.43)
(1.05)
1.82±0.06jk (1.34)
87.78±0.64a (69.55)
79.81±0.67cd (63.30)
(1.21)
2.37±0.03cd (1.53)
83.70±0.37b (66.19)
73.70±0.37jk (59.14)
(1.28)
2.70±0.06b (1.64)
81.85±0.98bc (64.79)
(56.79)
(3.00)
9.00±0.00a (3.00)
0.00±0.00k (0.36)
0.00±0.00o (0.36)
*Mean of three replications
Note: Figures in parentheses are square root transformed values for growth and arc sine transformed values for per cent inhibition over control.
Trang 8Table.2 PGPR and biocontrol efficacy of Trichoderma spp
Sl.
No
Trichoder
ma spp
Chitinase production
Siderophore Production
HCN Production
Ammonia production
ACC deaminase activity
IAA produce (ug/ml)
Phosphorous production (ug/ml)
*Mean of three replications
(+) indicates light color, (++) indicates dark color and (+++) indicates very dark color
(-) indicates absence
Plate.1 Rapid Screening of Trichoderma spp following modified Bell’s scale
S
2
Pathogen
Trang 9Plate.2 PGPR and biocontrol efficacy test of Trichoderma isolates
Chitinase production test Siderophore production test
HCN production test ACC deaminase production test
Ammonia production test IAA production test
Phosphorous solubilization
test
Trang 10Screening for plant growth promoting traits of
20 isolates revealed that all produced IAA
with TR 55 showing highest production (4.96
ug/ml) followed by others like TR 88 (4.70
ug/ml), TR 40 (3.22 ug/ml) and least in TR
116 (0.33 ug/ml) Also all produced
phosphorous with highest production in TR
106 (0.98 μg/ml) followed by TR 66 (0.75
ug/ml), TR 55 (0.72 ug/ml) and the least was
observed in TR 82 (0.03 ug/ml)
From 180 soil samples collected from all 11
districts of Meghalaya, 97 Trichoderma
isolates were obtained which showed that
Trichoderma isolates are predominant in
different habitat i.e., crop rhizosphere,
compost manure, sacred forest, coal mine and
lime stone The predomination of
Trichoderma in natural soils, decaying wood,
plant materials, crop rhizosphere were
reported by several workers (Kredics et al.,
2012; Kumar et al., 2012; Rai et al., 2016;
Jaisani and Pandey, 2017)
Out of 97 isolates screened by dual culture
against Pythium spp and R solani Kuhn.,
only 20 isolates colonized more than half of
the growth of pathogen i.e 50% overgrowth
TR 55 isolated from tomato rhizosphere was
found to be the most effective isolate against
both Pythium spp and R solani Kuhn,
showing an inhibition percentage of 89.26%
and 87.41% respectively, followed by other
isolates like TR 66, TR 122 and TR 136 The
antagonism of Trichoderma spp against
Pythium spp and R solani were widely
reported (Goud et al., 2015; Kotasthane 2015;
Waghunde et al., 2016; Kumari et al., 2016;
Naik et al., 2017; Rajendraprasad et al., 2017)
which supported the antagonism of
Trichoderma spp against Pythium spp and R
solani Kuhn during the present investigation
All 20 isolates screened for their PGPR and
biocontrol potential such as HCN, ammonia,
siderophore, IAA, chitinase, ACC deaminase
production and phosphate solubilisation showed that all 20 screened isolates were found positive for ACC deaminase production and 17 positive for chitinase production Out
of 20 screened isolates tested for other functional attributes (determining antagonistic potentials), 16 isolates were found positive for siderophore and ammonia production, whereas 13 isolates were positive for HCN production Screening for plant growth promoting traits of 20 isolates revealed that all produced IAA and Phosphorous with values ranging from 0.33 to 4.96 μg/ml and 0.03 to 0.98 μg/ml respectively The
production of lytic enzymes by Trichoderma
species is known as one of the major mechanisms for biocontrol activity against phytopathogenic fungi, involvement of chitinase in control of phytopathogens was
reported (Harman et al., 2004a; Harighi et al.,
2007, Azad et al., 2015, Thakar and Saraf
2015) HCN, siderophores and ammonia are
produced by many Trichoderma spp and are
believed to play a role in biological control of pathogens (Rawat and Tiwari, 2011; Qi and
Zhao, 2013, Zhang et al., 2016) Phosphate
solubilizing efficiency of different isolates of
Trichoderma was observed by many workers
like Tallapragada and Gudimi (2011);
Sarawanakumar et al., (2013); Promwee et
al., (2014): Borges Chagas et al., (2015),
Franca et al., (2017) ACC deaminase production of Trichoderma spp was reported
by several workers (Viterbo et al., 2010; Hermosa et al., 2012; Aban et al., 2017)
Aban and his co-workers also reported IAA production and phosphate solubilisation by
Trichoderma yunnanense and Trichoderma simmonsil which is similar to the present
findings
In conclusion, many Trichoderma isolates
were obtained from the crop rhizospheric soils in the 11 districts of Meghalaya, India Via screening test, 20 isolates showed the best antagonism against damping off pathogens